Episulfide compounds are used in a wide range of fields such as starting compounds for plastics, adhesives, drugs, insecticides, and herbicides.
Plastics formed by polymerizing the episulfide compounds have the properties of a high refractive index, a high Abbe's number, high heat resistance, and high strength and as such, have been used particularly in recent years as materials having better performance than ever in the field of optical materials.
The episulfide compounds are highly polymerizable and as such, are used as excellent fast curing adhesives compared with epoxy compounds conventionally generally used as adhesives.
Examples of one of methods for polymerizing the episulfide compounds include methods using polymerization catalysts, and some methods have been proposed so far.
For example, a method using a trivalent organic phosphorus compound, an amino group-containing organic compound, or a salt thereof has been proposed in Patent Literature 1. Moreover, a method using various onium salts as energy line-sensitive cationic polymerization initiators has been proposed in Patent Literature 2. Furthermore, a method using a zinc-porphyrin complex, a method using a salt of a thiol compound and 1,8-diazabicyclo[5.4.0]undec-7-ene, and a method using a metal thiolate compound having zinc or cadmium as a central metal have been proposed in Non Patent Literature 1, Non Patent Literature 2, and Non Patent Literature 3, respectively.